Evidence for an ABC-Type Riboflavin Transporter System in Pathogenic Spirochetes

ABSTRACT Bacterial transporter proteins are involved in the translocation of many essential nutrients and metabolites. However, many of these key bacterial transport systems remain to be identified, including those involved in the transport of riboflavin (vitamin B2). Pathogenic spirochetes lack rib...

Descripción completa

Guardado en:

Detalles Bibliográficos
Autores principales:	Ranjit K. Deka, Chad A. Brautigam, Brent A. Biddy, Wei Z. Liu, Michael V. Norgard
Formato:	article
Lenguaje:	EN
Publicado:	American Society for Microbiology 2013
Materias:	Microbiology QR1-502
Acceso en línea:	https://doaj.org/article/21fa4c6d491047d380207230cd3759ad
Etiquetas:	Agregar Etiqueta Sin Etiquetas, Sea el primero en etiquetar este registro!

id	oai:doaj.org-article:21fa4c6d491047d380207230cd3759ad
record_format	dspace
spelling	oai:doaj.org-article:21fa4c6d491047d380207230cd3759ad2021-11-15T15:40:23ZEvidence for an ABC-Type Riboflavin Transporter System in Pathogenic Spirochetes10.1128/mBio.00615-122150-7511https://doaj.org/article/21fa4c6d491047d380207230cd3759ad2013-03-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mBio.00615-12https://doaj.org/toc/2150-7511ABSTRACT Bacterial transporter proteins are involved in the translocation of many essential nutrients and metabolites. However, many of these key bacterial transport systems remain to be identified, including those involved in the transport of riboflavin (vitamin B2). Pathogenic spirochetes lack riboflavin biosynthetic pathways, implying reliance on obtaining riboflavin from their hosts. Using structural and functional characterizations of possible ligand-binding components, we have identified an ABC-type riboflavin transport system within pathogenic spirochetes. The putative lipoprotein ligand-binding components of these systems from three different spirochetes were cloned, hyperexpressed in Escherichia coli, and purified to homogeneity. Solutions of all three of the purified recombinant proteins were bright yellow. UV-visible spectra demonstrated that these proteins were likely flavoproteins; electrospray ionization mass spectrometry and thin-layer chromatography confirmed that they contained riboflavin. A 1.3-Å crystal structure of the protein (TP0298) encoded by Treponema pallidum, the syphilis spirochete, demonstrated that the protein’s fold is similar to the ligand-binding components of ABC-type transporters. The structure also revealed other salient details of the riboflavin binding site. Comparative bioinformatics analyses of spirochetal genomes, coupled with experimental validation, facilitated the discovery of this new ABC-type riboflavin transport system(s). We denote the ligand-binding component as riboflavin uptake transporter A (RfuA). Taken together, it appears that pathogenic spirochetes have evolved an ABC-type transport system (RfuABCD) for survival in their host environments, particularly that of the human host. IMPORTANCE Syphilis remains a public health problem, but very little is known about the causative bacterium. This is because Treponema pallidum still cannot be cultured in the laboratory. Rather, T. pallidum must be cultivated in laboratory rabbits, a restriction that poses many insurmountable experimental obstacles. Approaches to learn more about the structure and function of T. pallidum’s cell envelope, which is both the physical and functional interface between T. pallidum and its human host, are severely limited. One approach for elucidating T. pallidum’s cell envelope has been to determine the three-dimensional structures of its membrane lipoproteins, molecules that serve many critical survival functions. Herein, we describe a previously unknown transport system that T. pallidum uses to import riboflavin, an essential nutrient for the organism’s survival. Moreover, we found that this transport system is present in other pathogenic spirochetes. This is the first description of this new type of bacterial riboflavin transport system.Ranjit K. DekaChad A. BrautigamBrent A. BiddyWei Z. LiuMichael V. NorgardAmerican Society for MicrobiologyarticleMicrobiologyQR1-502ENmBio, Vol 4, Iss 1 (2013)
institution	DOAJ
collection	DOAJ
language	EN
topic	Microbiology QR1-502
spellingShingle	Microbiology QR1-502 Ranjit K. Deka Chad A. Brautigam Brent A. Biddy Wei Z. Liu Michael V. Norgard Evidence for an ABC-Type Riboflavin Transporter System in Pathogenic Spirochetes
description	ABSTRACT Bacterial transporter proteins are involved in the translocation of many essential nutrients and metabolites. However, many of these key bacterial transport systems remain to be identified, including those involved in the transport of riboflavin (vitamin B2). Pathogenic spirochetes lack riboflavin biosynthetic pathways, implying reliance on obtaining riboflavin from their hosts. Using structural and functional characterizations of possible ligand-binding components, we have identified an ABC-type riboflavin transport system within pathogenic spirochetes. The putative lipoprotein ligand-binding components of these systems from three different spirochetes were cloned, hyperexpressed in Escherichia coli, and purified to homogeneity. Solutions of all three of the purified recombinant proteins were bright yellow. UV-visible spectra demonstrated that these proteins were likely flavoproteins; electrospray ionization mass spectrometry and thin-layer chromatography confirmed that they contained riboflavin. A 1.3-Å crystal structure of the protein (TP0298) encoded by Treponema pallidum, the syphilis spirochete, demonstrated that the protein’s fold is similar to the ligand-binding components of ABC-type transporters. The structure also revealed other salient details of the riboflavin binding site. Comparative bioinformatics analyses of spirochetal genomes, coupled with experimental validation, facilitated the discovery of this new ABC-type riboflavin transport system(s). We denote the ligand-binding component as riboflavin uptake transporter A (RfuA). Taken together, it appears that pathogenic spirochetes have evolved an ABC-type transport system (RfuABCD) for survival in their host environments, particularly that of the human host. IMPORTANCE Syphilis remains a public health problem, but very little is known about the causative bacterium. This is because Treponema pallidum still cannot be cultured in the laboratory. Rather, T. pallidum must be cultivated in laboratory rabbits, a restriction that poses many insurmountable experimental obstacles. Approaches to learn more about the structure and function of T. pallidum’s cell envelope, which is both the physical and functional interface between T. pallidum and its human host, are severely limited. One approach for elucidating T. pallidum’s cell envelope has been to determine the three-dimensional structures of its membrane lipoproteins, molecules that serve many critical survival functions. Herein, we describe a previously unknown transport system that T. pallidum uses to import riboflavin, an essential nutrient for the organism’s survival. Moreover, we found that this transport system is present in other pathogenic spirochetes. This is the first description of this new type of bacterial riboflavin transport system.
format	article
author	Ranjit K. Deka Chad A. Brautigam Brent A. Biddy Wei Z. Liu Michael V. Norgard
author_facet	Ranjit K. Deka Chad A. Brautigam Brent A. Biddy Wei Z. Liu Michael V. Norgard
author_sort	Ranjit K. Deka
title	Evidence for an ABC-Type Riboflavin Transporter System in Pathogenic Spirochetes
title_short	Evidence for an ABC-Type Riboflavin Transporter System in Pathogenic Spirochetes
title_full	Evidence for an ABC-Type Riboflavin Transporter System in Pathogenic Spirochetes
title_fullStr	Evidence for an ABC-Type Riboflavin Transporter System in Pathogenic Spirochetes
title_full_unstemmed	Evidence for an ABC-Type Riboflavin Transporter System in Pathogenic Spirochetes
title_sort	evidence for an abc-type riboflavin transporter system in pathogenic spirochetes
publisher	American Society for Microbiology
publishDate	2013
url	https://doaj.org/article/21fa4c6d491047d380207230cd3759ad
work_keys_str_mv	AT ranjitkdeka evidenceforanabctyperiboflavintransportersysteminpathogenicspirochetes AT chadabrautigam evidenceforanabctyperiboflavintransportersysteminpathogenicspirochetes AT brentabiddy evidenceforanabctyperiboflavintransportersysteminpathogenicspirochetes AT weizliu evidenceforanabctyperiboflavintransportersysteminpathogenicspirochetes AT michaelvnorgard evidenceforanabctyperiboflavintransportersysteminpathogenicspirochetes
_version_	1718427752115208192

Evidence for an ABC-Type Riboflavin Transporter System in Pathogenic Spirochetes

Ejemplares similares